Molecules 2014, 19(5), 6184-6201; doi:10.3390/molecules19056184
Article

Antiprotozoal Activity of Buxus sempervirens and Activity-Guided Isolation of O-tigloylcyclovirobuxeine-B as the Main Constituent Active against Plasmodium falciparum

1,†email, 2email, 2email, 3,4email, 3,4email and 1,* email
Received: 14 March 2014; in revised form: 9 May 2014 / Accepted: 12 May 2014 / Published: 15 May 2014
This is an open access article distributed under the Creative Commons Attribution License which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
Abstract: Buxus sempervirens L. (European Box, Buxaceae) has been used in ethnomedicine to treat malaria. In the course of our screening of plant extracts for antiprotozoal activity, a CH2Cl2 extract from leaves of B. sempervirens showed selective in vitro activity against Plasmodium falciparum (IC50 = 2.79 vs. 20.2 µg/mL for cytotoxicity against L6 rat cells). Separation of the extract by acid/base extraction into a basic and a neutral non-polar fraction led to a much more active and even more selective fraction with alkaloids while the fraction of non-polar neutral constituents was markedly less active than the crude extract. Thus, the activity of the crude extract could clearly be attributed to alkaloid constituents. Identification of the main triterpene-alkaloids and characterization of the complex pattern of this alkaloid fraction was performed by UHPLC/+ESI-QTOF-MS analyses. ESI-MS/MS target-guided larger scale preparative separation of the alkaloid fraction was performed by ‘spiral coil-countercurrent chromatography’. From the most active subfraction, the cycloartane alkaloid O-tigloylcyclovirobuxeine-B was isolated and evaluated for antiplasmodial activity which yielded an IC50 of 0.455 µg/mL (cytotoxicity against L6 rat cells: IC50 = 9.38 µg/mL). O-tigloylcyclovirobuxeine-B is thus most significantly responsible for the high potency of the crude extract.
Keywords: Buxus sempervirens; antiprotozoal activity; cycloartane alkaloids; Plasmodium falciparum; Trypanosoma brucei rhodesiense; Trypanosoma cruzi; Leishmania donovani; spiral-coil countercurrent chromatography
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MDPI and ACS Style

Althaus, J.B.; Jerz, G.; Winterhalter, P.; Kaiser, M.; Brun, R.; Schmidt, T.J. Antiprotozoal Activity of Buxus sempervirens and Activity-Guided Isolation of O-tigloylcyclovirobuxeine-B as the Main Constituent Active against Plasmodium falciparum . Molecules 2014, 19, 6184-6201.

AMA Style

Althaus JB, Jerz G, Winterhalter P, Kaiser M, Brun R, Schmidt TJ. Antiprotozoal Activity of Buxus sempervirens and Activity-Guided Isolation of O-tigloylcyclovirobuxeine-B as the Main Constituent Active against Plasmodium falciparum . Molecules. 2014; 19(5):6184-6201.

Chicago/Turabian Style

Althaus, Julia B.; Jerz, Gerold; Winterhalter, Peter; Kaiser, Marcel; Brun, Reto; Schmidt, Thomas J. 2014. "Antiprotozoal Activity of Buxus sempervirens and Activity-Guided Isolation of O-tigloylcyclovirobuxeine-B as the Main Constituent Active against Plasmodium falciparum ." Molecules 19, no. 5: 6184-6201.

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